The $5.1 million number is not her taxable income. It's her taxable income (roughly $2.4 million) plus tax-exempt interest income ($2.7 million).
I have no idea where the $20 million figure came from. The Kerry campaign noted that her TRUSTS also allegedly pay tax. Perhaps the other $15 million was actually earned by them.
Interesting.
I guess I'm too stupid to file the Kerry-Heinz-Kerry way.